June 5, 2023


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There is a serious gap in our knowledge of the universe. Scientists still dodge the Hubble constant

Almost exactly a hundred years ago, attempts began to estimate what’s called the Hubble-Limeter constant, a value that describes the expansion rate of the universe as a function of time. Over the years, several independent methods have been developed to determine the Hubble-Limeter constant. Scientists using currently visible stars and galaxies to identify them have obtained similar results that oscillate around a value of 73 km/sec/Mpc ± 1.0 km/sec/Mpc. It just means that the average speed of a galaxy moving away from us increases by 73 km/sec per megaparsec (1 megaparsec = 3.26 million light-years) from Earth. This value is obtained on the basis of measurements of the distance to the Cepheids (variable stars thousands of times brighter than the Sun, which regularly change their brightness as a result of pulsations due to changes in the size and temperature of the star), and then on the basis of Type Ia supernovae, which scientists have been using for years They are standard candles. Due to the fact that the absolute brightness of both Cepheids and Type Ia supernovae is always the same, the brightness observed from Earth makes it possible to accurately determine the distance between them.

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The problem is that scientists who measure the value of the Hubble-Lematter constant using cosmic background radiation, that is, the subtle glow emitted only 360,000 years after the Big Bang, get a value close to 67.4 km/sec/mc. This value estimated by the Planck satellite sent into orbit by the European Space Agency is subject to a measurement uncertainty of 0.5 km/s/Mpa. So there must be an error somewhere.

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What is the correct Hubble constant?

Hubble tension – This term is often used to describe the discrepancy between these two values ​​(Hubble tension). If subsequent measurements using both methods always show the same different values, this must mean that we have a serious gap in our knowledge of the fundamental physical laws that govern the universe.

in Latest published article In the Journal of Astronomy & Astrophysics, scientists from the Standard Candles and Distance Candles Research Group at the EPFL Institute of Physics report the most accurate distance measurements yet to Cepheids. It was prepared on the basis of data collected by the European Space Observatory Gaia. The scientists focused their measurements on Cepheid star clusters that contain at least a few hundred stars. The researchers tested whether the stars of the cluster move together across the Milky Way. The velocity and distance measurements for each star in the cluster were able to increase the distance determination accuracy to ±0.9%. impact? The expansion rate of the universe estimated in this way is 73 km/s/Mpc.

This means that the researchers were able to improve the accuracy of determining the Hubble constant while at the same time strengthening the previous result. The difference between this measurement and the microwave background measurement of 5.6 km/s/Mpc is becoming more apparent. So there can only be one conclusion: it is clear that we have not noticed something in the Universe yet, and our description of it so far is only an approximation. The universe is not what it appears to us. This deficiency could greatly affect our understanding of dark matter, space-time, and gravity.

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